How to Interpret the Forecast Map

Lightning Map

The following are important terms used when interpreting the forecast map.

Date and Time

The validation date and valid time are located in the box on the bottom left hand corner. The forecast map is issued by 10:00 MDT daily during the forest fire season and valid for 17:00 MDT.

The 500mb heights forecasted for the afternoon

The red long-dashed lines indicate the forecasted 500mb height field. This field is intended to give an idea of the movement of the weather systems affecting the forecast zones. Other significant features such as upper ridges or troughs will be mentioned in the synopsis.

The surface map features

The solid black lines indicate the surface pressure field at every 2mb interval. Circulations of low or high pressure are also labeled as "L" or "H", while frontal boundaries are indicated with their corresponding symbols. Significant features that impact fire weather operations are always mentioned in the AM synopsis.

Included for each forecast zone are:

  • forecast maximum temperatures
  • forecast minimum relative humidities
  • type of precipitation
  • wind speed with direction

These values are located in the small boxes located in each forecast zone. This data is taken directly from the AM forecast.

For questions about how to interpret the forecast map, contact the Weather Section at:


Updated: Mar 1, 2017